1. Field of the Invention
The present invention relates to an image search server which is connected to a database storing images and to an image display terminal, and which searches the database in response to a request of the image display terminal to output a result of the search on the display terminal. More specifically, the present invention relates to an image search server comprising a function to retain images fetched from a database in storing means thereof, and to search for an image within the server, i.e. what is called a “pre-fetch function”, and also to an image search method therefor. The present invention further relates to a medical image display system employing a medical image server comprising the pre-fetch function as described above.
2. Description of the Related Art
Images recorded by various kinds of image recording modalities for CT, MRI, CR and the like in a medical facility such as a hospital have been stored in a large capacity recording medium such as an optical disc. In this specification, an apparatus for storing images of this kind is called an “image archiving apparatus”. Medical images are input from each image recording modality to an image archiving apparatus directly or via an image server connected to the archiving apparatus through a network, and the images are stored in the archiving apparatus.
The medical images are output from the image archiving apparatus to a terminal when the image server receives an output request from the terminal.
However, it takes a long time to output an image on a terminal if the image server fetches the image after receiving an output request from the terminal. Therefore, many medical image servers have what is called a “pre-fetch function” to retain images having the potential for output-request in a hard disc thereof before an actual output request is received. Medical image servers having the pre-fetch function have been configured in such a manner that all images recorded or images of patients subjected to examinations or diagnoses in a recent predetermined period are stored therein. When pre-fetching is carried out in this manner, it takes a long time for the image server to fetch the images from an image archiving apparatus and the image server needs a large-capacity hard disc, since the amount of the images to be retained in the server is large. Furthermore, in that case, a user has to select a necessary image out of the large volume of pre-fetched images, which is also time-consuming. Therefore, a first object of the present invention is to provide a medical image server and an image acquisition apparatus enabling reduction in pre-fetched images while maintaining a complete pre-fetching function, and a medical image display system which employs the above medical image server with the pre-fetch function to display medical images efficiently.
Many of the image recording modalities described above use a predetermined type of character among various character types such as the Japanese syllabary and the Roman alphabet for inputting information showing the name of a patient, for example. In this case, text information recorded in the database together with the images naturally uses the predetermined character type. Meanwhile, many terminals such as diagnostic workstations use only one type of character. In a situation like this, when a search request specifying the name of a patient in the Japanese syllabary is output from a terminal such as a diagnostic workstation or the like, the image may not be found due to the name of the patient being written in the Roman alphabet in the database, even if the image actually exists in the database. Therefore, a second object of the present invention is to provide a medical image searching method and a medical image search apparatus enabling a thorough search of a database regardless of the character type used in a search requesting apparatus and in the database, and enabling a proper notification of a search result to the search requesting apparatus.
In a conventional image search server having an image processing function, an image having been found is transferred from a database to an image display terminal via the image search server even if image processing is unnecessary for the image search server due to the image processing function of the image display terminal. As a result, it is time-consuming for the image to reach the image display terminal. Therefore, a third object of the present invention is to provide an image search server enabling a fast transfer of an image having been found from a database to an image display terminal retaining an image processing function which can be used as requested.
The image search server having the above search function is often configured in such a manner that the images of frequent use among the images in the database are retained in storing means thereof. When an image display terminal requests a search of an image from the image search server having the above configuration, the images of frequent use can be searched for promptly and an image can be obtained by searching all image information stored in the database. However, in such a conventional image search server having the function to search the storing means within the server, the database is searched unnecessarily in some cases, since the database is searched after the storing means within the server is searched. As a result, a response of the search is slow. Therefore, a fourth object of the present invention is to provide an image search server and an image searching method enabling a search of an image in a highly responsive manner while enabling a search of all databases as required.